Indian Institute of Technology, Patna

Rishi Raj is an Assistant Professor in the Department of Mechanical Engineering at IIT Patna. He received his B.Tech. degree from IIT Guwahati in 2006 and a PhD from the University of Maryland College Park in 2010. Prior to joining IIT Patna in 2013, he was the Battelle Postdoctoral Fellow in the Device Research Laboratory at MIT. His group investigates thermal and fluid transport during the liquid–vapour phase change for various energy, water, and thermal management applications. His work has been acknowledged with the 2018 INAE Young Engineer Award and various best papers awards in conferences and workshops, among others. Rishi Raj was selected Associate in 2018.


SESSION 1B: Inaugural Lectures by Fellows/Associates

E D Jemmis

Development of two-phase heat sinks for earth and microgravity thermal management applications

Boiling utilizes the latent heat of vapourization of a fluid to enable high heat transfer in applications such as cooling of electronics, cryogenic fuel storage, refrigeration and air conditioning. However, boiling behaviour is altered and the advantage of high heat transfer on earth is lost due to absence of buoyancy-induced bubble removal in zero gravity of space. In this regard, the speaker has developed a passive bubble removal mechanism, which uses surfactants found in soaps and detergents to facilitate more than 4x enhancement in heat transfer in comparison to boiling with pure water. This strategy is currently being implemented in a two-phase heat spreader for hot spot mitigation in spacecrafts. Similarly, boiling in the confinement of microchannels does not allow easy bubble removal even on earth. In this regard, he has developed an ingenious pulse dampener, which adaptively removes the excess vapour generated in the microchannels. This strategy allows relatively high heat transfer (~MW/m^2) in comparison to the typical heat sinks without pulse-dampener (~500 kW/m^2). The pressure drop penalty is also small in comparison to the other state-of-the-art technologies.